A complicating factor is that of origin-destination control ("O&D control"). Someone purchasing a ticket from Melbourne to Sydney (as an example) for A$200 is competing with someone else who wants to fly Melbourne to Los Angeles through Sydney on the same flight, and who is willing to pay A$1400. Should the airline prefer the $1400 passenger, or the $200 passenger plus a possible Sydney-Los Angeles passenger willing to pay $1300? Airlines have to make hundreds of thousands of similar pricing decisions daily.
Airline financing is quite complex, since airlines are highly leveraged operations. Not only must they purchase (or lease) new airliner bodies and engines regularly, they must make major long-term fleet decisions with the goal of meeting the demands of their markets while producing a fleet that is relatively economical to operate and maintain; comparably Southwest Airlines and their reliance on a single airplane type (the Boeing 737 and derivatives), with the now defunct Eastern Air Lines which operated 17 different aircraft types, each with varying pilot, engine, maintenance, and support needs.
Little by little, though, Milos is being discovered. Instagram is saturated with no-filter shots of the undulating cliffs at Sarakiniko, the bottle-green swimming hole at Papafragas, and colourful, rickety syrmata, tiny boat houses wedged between rock and sea. (You’ll find the best photo opportunities at Klima and Mandrakia). This painterly landscape was shaped by the minerals that have long been a source of wealth – obsidian, alum, barite and sulphur, which still bubbles up in the island’s many hot springs. As the 11,000-year-old mining industry is gradually giving way to tourism, several chic hotels have made an appearance. Go now, before the trickle of visitors turns into a tide.
Bilateral agreements are based on the "freedoms of the air", a group of generalized traffic rights ranging from the freedom to overfly a country to the freedom to provide domestic flights within a country (a very rarely granted right known as cabotage). Most agreements permit airlines to fly from their home country to designated airports in the other country: some also extend the freedom to provide continuing service to a third country, or to another destination in the other country while carrying passengers from overseas.

It’s best to visit Greek islands within the same group. For example, I wouldn’t recommend visiting Corfu and Santorini on the same trip as they’re on opposite sides of the country. Instead, visit islands in the same island group: the Cyclades, the Sporades, the Dodecanese, the Ionian, the Saronic, and the Northeastern Aegean. For one, they’re close to each other. And two, they have frequent ferry connections with each other. For first time visitors to Greece, the Cyclades make the most natural and convenient introduction.
The Greek islands have beautiful weather in the months just before and after peak season. It’s a great time to see the islands, save money, avoid the crowds, and still have great weather (though not as hot as July and August). If you want to see the super-popular islands of Santorini, Rhodes, Corfu, and Crete without the tourists then this is a great time to visit.